Mantis Windows problem

No, the stacks are all independent. The needed configuration is in the installation folder, no registry tweaking involved :)The only problem that I think could happen would be if you install the new stack with the RubyStack services off. That way, both stacks will use the same ports, so you can only run one at a time. If you install the new stack with the RubyStack services running, you will be prompted to choose different ports for the servers, as the default ones will be already taken.